Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

820
FXUS63 KLOT 012330
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
630 PM CDT Mon Jun 1 2026

.KEY MESSAGES...

- Generally dry conditions through mid-week with
  seasonable temperatures inland and cooler conditions near the
  lake.

- Rain chances return Friday and may linger through the weekend.

&&

.DISCUSSION...
Issued at 201 PM CDT Mon Jun 1 2026

A shortwave trough continues to dive southward across the
northern Great Lakes with a band of mid-level moisture being
noted ahead of the trough from northern MN to the Ohio River
Valley. While a few radar echoes have developed ahead of the
shortwave within the moisture axis, the high cloud bases
(7000-8000 ft) and dry sub-cloud layer (temp-dew point spreads
20-30 degrees) are preventing anything from reaching the
surface. Therefore, dry conditions are expected to prevail as
the shortwave pivots through this evening with skies expected to
gradually clear behind the wave. Despite the mostly to
completely cloudy skies, temperatures have warmed into the 70s
in many places with even a few sites tagging the lower 80s. The
exception though is closer to Lake Michigan where onshore winds
have capped temperatures in the mid to upper 60s. Temperatures
will likely remain nearly steady through sunset before cooling
into the lower 50s overnight.

High pressure will build back into the Great Lakes late tonight
into Tuesday morning and will persist through the middle of the
week. This will result in mostly sunny skies and generally
light east-northeast winds through Wednesday before winds turn
more southeasterly on Thursday. Temperatures during this period
will remain in the seasonable to seasonably warm category with
highs in the upper 70s to mid-80s each day. However, with
persistent onshore winds Tuesday and Wednesday, temperatures
near the lake will be notably cooler in the 60s to around 70.

While we enjoy the pleasant spring weather, the broad upper low
that is spinning over the Mountain West will begin to drift
eastward as a deepening Pacific trough moves onshore. As the
upper low moves east it is forecast to broaden into a shortwave
trough which will in turn begin to push the baroclinic zone
stalled across the Plains eastward as well. The forcing from the
baroclinic zone and trough should result in an uptick in shower
and thunderstorm coverage across the Midwest by Thursday that
will eventually spread into the Great Lakes during the Friday
and Saturday timeframe. While guidance is in generally decent
agreement on this systems evolution through weeks end, there is
still some uncertainty in exact timing rain will return locally
due to intensity differences with the aforementioned eastward
propagating trough. Regardless, it does look as if a period of
wet weather will impact the area to close out the week and begin
the weekend.

In the wake of this system is where forecast confidence becomes
much lower as guidance varies greatly on how the pattern will
evolve behind the initial trough. The GFS/GEFS solutions
continue to favor the initial trough arriving stronger and as
result having a more formidable frontal zone to push through
northern IL and northwest IN. Therefore, in the wake of the
front the GFS/GEFS indicates stronger ridging redeveloping and
resulting in another period of tranquil weather with persistent
east-northeast winds from Sunday into next week. However, the
Euro and Canadian deterministic and ensemble solutions are
notably weaker with the initial trough and therefore have a much
slower and more diffuse frontal zone moving through. Due to the
weaker forcing, the Euro/Canadian solutions show weaker ridging
redeveloping on Sunday and thus allowing a secondary shortwave
to eject out of the southern Plains towards the mid-Mississippi
Valley and western Great Lakes. If this solution pans out then
we would be looking at a shift towards a warmer and more stormy
pattern with several periods of showers and thunderstorms
possible this weekend into next week.

At this stage, the high degree of uncertainty makes confidence
too low to favor any particular solution. So our official
forecast will maintain some chances for showers and storms
through the weekend and into next week as the NBM`s
probabilistic guidance favors the Euro/Canadian solutions, but
will need to watch this period closely for emerging trends. That
said, anyone with outdoor plans this weekend or next week
should keep checking back for updates as the extended forecast
is likely going to shift a lot over the coming days as guidance
tries to resolve this pattern.

Yack

&&

.AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 630 PM CDT Mon Jun 1 2026

No significant concerns for the 00Z TAFs.

The forecast area remains on the southern periphery of an area
of surface high pressure over Ontario. Dry northeast low-level
flow will persist through the period, with a slight reinforcement
later tonight as the high builds south into lower Michigan. It
will likely be slightly breezier (northeast winds 12-15 kts or
so) on Tuesday, but otherwise VFR will continue with little
change to current conditions.

Ratzer

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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